chapter 2 radiography

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chapter 2 radiography
2014-08-20 20:18:44
chapter radiography

chapter 2 radiography
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  1. primary radiation
    the radiation that leaves the tube
  2. radiation field
    the squared area of the x-ray beam that strikes the patient and x-ray table
  3. central ray
    an imaginary line in the center of the x-ray beam and perpendicular to the long axis of the x-ray tube
  4. remnant radiation
    the radiation that exits or leaves the patient's body and exposes film
  5. latent image
    unseen , an image contained in the film before it is processed
  6. x-ray beam
    x-ray that form a triangular-shape
  7. tube port
    x-rays that are created exit the housing through an opening
  8. attenuation
    absorption of the x-ray beam

    attenuation x-ray can be total absorbed within the body. the patient is the primary source of scatter
  9. scatter radiation
    radiation travels out from the absorbing matter in all directions , not easily controlled. causing unwanted exposure to the (IR) image receptor
  10. image receptor (IR)
    the device that receives the energy of the x-ray beam and forms the image of the body part. The IR may be a screen-film cassette, a computed radiography CR imaging plate or a solid-state digital receptor
  11. scatter radiation fog
    the unwanted image exposer caused by scatter radiation
  12. X-ray Tube
    • –Source
    • of x-rays

    • –Surrounded
    • by lead lining

    • –Has
    • Tube port for x-rays to exit
  13. Primary X-Ray beam
    Triangular Shaped diverging beam leaves the tube
  14. Radiation Field
    Squared area that exposes the patient
  15. Central Ray
    Imaginary line in the center of the x-ray beam

    Used to align the Tube with the anatomy of interest
  16. 3 Types of Radiation
    • Primary
    • Scatter
    • Remnant
  17. Primary Radiation is
    • The x-ray beam that leaves
    • the tube and is unattenuated, except by air.  Its direction and location are predictable
    • and controllable.
  18. Scatter Radiation
    • Radiation from the primary beam that is
    • randomly scattered within or outside of the body.  It travels in all directions from the patient and is very difficult to control.  Generally, it has less energy than the primary beam.
  19. Remnant radiation
    • What remains of the primary beam after it
    • has been attenuated by matter (the patient). 
    • Tissues of different density, or atomic number, in the body absorb x-rays differently and therefore emit x-rays differently. The remnant beam contains a varied pattern of x-ray energies that reflects the different
    • absorption rates.  The pattern of the
    • remnant radiation creates the x-ray image.
  20. Computed Radiography Image Receptor
    •Cassette with Phosphor Imaging Plate

    •Exposed by Remnant Radiation and forms the latent (invisible) image

    •Post processing, forms manifest (visible) image
  21. CR Reader
    •Exposed IR is inserted into the CR reader

    • •Unit scans the Phosphor coated plate with a 
    • laser

    •Digitizes the image and makes it viewable on the workstation monitor
  22. Workstation
    •View image

    • •Adjust
    • window and leveling

  23. X-Ray Tube motions
    • •Tube
    • Motions

    • –Longitudinal
    • •Along the long axis of the x-ray table

    • –Transverse
    • •Along the short axis of the x-ray table

    • –Vertical
    • •Up and down

    • –Rotational
    • •Allows tube stand to turn on its axis

    • –Angular
    • •Tilt or Roll with the long axis of the x-ray table
  24. Electrical or Magnetic Locks
    • move the tube, make sure to press the correct release or it will cause damage
    • to the x-ray system


    • Located
    • in the Ceiling Tracts.  It stops the tube
    • in a specific location



  25. Collimator
    • •Box
    • underneath of the x-ray tube

    • •Limits
    • the size of the x-ray beam
  26. X-Ray Table
    •Secured to the floor

    • •3 Movements possible
    • –Vertical
    • –Tilt
    • –Floating table top

    •Contains Grid below table above cassette

    •Pull out tray for centering and part of grid

    •Bucky-the grid and pull out tray
  27. Adverse Incidents
    •Most common at upright bucky

    –Patient Falling

    –Never leave patient alone on the table

    –Always watch the patient through the window as making an exposure
  28. Radiation Safety
    • •Source is the x-ray tube
    • –Avoid primary beam

    •X-Rays travel at the speed of light

    •Travel in straight lines

    • •Must stay behind the control booth
    • Avoids scatter

    •No risk of exposure before or after x-ray

    •Never hold patients